In RF devices, digital representations of RF signal levels and/or measured field strengths are used by digital circuitry. Because RF signal levels are generally measured in decibels (dB), which are logarithmic representations of the RF power level, linear ADCs that convert voltages representing the RF signal levels do not provide the desired precision at lower levels. ADCs with a logarithmic response may be used to overcome this issue, but are difficult and/or expensive to fabricate. Alternatively, the output of linear ADCs may be converted digitally to a logarithmic output, but linear ADCs may not have the precision in the lower range to provide an accurate result. Similar fabrication issues exist for DACs in which a non-linear response, such a logarithmic response, is desired.
Thus, there are general needs for DACs having a non-linear response, and methods for converting a digital input to an analog voltage. There are also general needs for DACs having a non-linear response that are less expensive and/or that require less precision to fabricate.